Electrically operated switching valve

摘要

An electrically operated switching valve comprising a valve housing provided with a pair of opposed valve ports, a valve member disposed between the valve ports for co-operation therewith and a snap-action valve actuating device for actuating said valve member alternately into engagement with the valve ports. The valve actuating device includes a rectangular plate which is bent in one direction along the longitudinal center line and a strap member extending between diagonally opposite corners of the plate and secured thereto. The strap member has a length which is smaller than the diagonal dimension of the plate so that the plate is deflected under tension applied by the strap member in the opposite direction along the transverse center line of the plate. The strap member is associated with an electric heating wire so that it is heated when the wire is energized. Since the strap member has a coefficient of thermal expansion which is greater than that of the plate so that it is expanded by a greater extent than the plate when heated by the wire allowing the plate to return with snap action to its undeflected position.